This invention relates to an amorphous alloy for magnetic head core with high permeability, high saturation flux density and low magnetic after-effect.
The characteristics of a head for a high density magnetic recording and reproducing system require high sensitivity, low distortion and low noise in a broad frequency range, and good wear resistivity and a long life.
The so far known materials for magnetic head core include, for example, ferrite materials such as Mn-Zn ferrite, etc. and alloy materials such as sen-alloy, but the characteristics of these materials are not always satisfactory. That is, the ferrite materials have good high frequency characteristics and high wear resistivity. However, the magnetic head made from the ferrite material has high distortion owing to a low saturation flux density, particularly when a metal powder tape with high coercive force is used as a magnetic recording medium. Furthermore, it generally has much noise peculiar to the ferrite material. On the other hand, the alloy material has high saturation flux density, and thus the magnetic head made from it has low distortion and low noise, but the high frequency characteristics are not preferable.
Several years ago, amorphous alloy as a new material satisfying the requirements for the magnetic head core for high density magnetic recording and reproducing system was found and regarded as promising. Metal takes a crystal form in the ordinary solid state, where the constituent atoms are regularly arranged, but under specific conditions the atoms are in a randomly arranged state similar to a liquid state. The metal under the specific conditions is called amorphous metal in contrast to the ordinary crystalline metal. The amorphous metal consisting of appropriate components in an appropriate composition has such a special structure that it has peculiar properties different from those of crystalline alloy and may show high hardness, high tensile strength, high corrosion resistivity, soft magnetic properties, etc. It is readily expectable that a magnetic head with good performance can be obtained by utilizing these characteristics of the amorphous alloy.
However, there has been no actual case of producing and selling a magnetic head with a core of amorphous alloy in a commercial scale. Since the amorphous alloy is in a non-equilibrium phase, its distinguished characteristics are liable to change, and it is difficult to produce products stable against the prolonged use. This is one of the greatest reasons. Actually it has been found that, when a magnetic head was made from the well known amorphous alloy, its characteristics were changed within a few months even at room temperature.
Furthermore, the amorphous alloy is distinguished in some characteristics, and is not always distinguished in other characteristics. Thus, it has not been a distinguished material for magnetic head core from the overall point of view.
The following references are cited to show the state of art; (i) Japanese Laid-open Patent Application No. 65395/76, (ii) Japanese Laid-open Patent Application No. 77899/76 and (iii) Japanese Laid-open Patent Application No. 105525/77.